Medical imaging through the use of radionuclides has become a critical component in the diagnosis and treatment of many diseases and conditions. A device, such as a gamma camera, can be used to detect radiation emitted from radioisotopes. These types of devices are often used by physicians within a sterile surgical field.
One or more collimators are typically employed in such a device in order to facilitate the desired imaging. A collimator can be used to reduce stray or unwanted radiation so that it does not reach the detector portion of the imaging device. Stray or scattered radiation, e.g., radiation that is not travelling parallel from the imaged area, may significantly impair the resolution of the device.
In certain types of radiation imaging, it is necessary to frequently change collimators. Collimators may be changed for several reasons, including adapting the radiation imager to a different energy, changing its resolution or count rate, or changing the angle of view.
A surgeon may have the desire to initially operate the gamma camera at a rapid speed, with low resolution, as he begins the process of localizing a target area. In such cases, the gamma camera might be operated with simply one collimator attached. Once the surgeon approaches a suspect lesion, he may wish to increase the resolution of the device. He may then add one or more additional collimators until the desired resolution is achieved.
In traditional assemblies, the collimators are retained by screws within flanges. With intraoperative radiation imagers, the devices are usually operated within a disposable sheath or sleeve in order to maintain the integrity of the sterile field. The use of a sleeve is a preferred method of operation as sterilization of the entire gamma camera assembly is more problematic due to the numerous surfaces and crevices on the assembly. If a different collimator is required, the device must be removed from the sterile field, the collimator changed using tools, the device inserted in a new sterile sheath, and then returned to the sterile field. This method of exchange is time-intensive and may result in a disruption of the surgical procedure. The use of screws/flanges has further drawbacks in that it requires an inert area within the collimator structure that in some cases inhibits the optimum use of the collimator.
It is therefore preferable to have a collimator that can be easily and quickly changed. It is further desirable to have a device and method which insures the accurate and precise positioning of the collimators in the assembled radiation imager.